Drive mechanism having overload release means



United States Patent O 3,406,583 DRIVE MECHANISM HAVING OVERLOAD RELEASEMEANS John P. Baier, Rochester, N.Y., assignor to General MotorsCorporation, Detroit, Mich., a corporation of Delaware Filed Jan. 30,1967, Ser. No. 612,719 6 Claims. (Cl. 74-411) ABSTRACT F THE DISCLOSUREIn a preferred form, this disclosure relates to a clutch arrangementwhich includes a gear having a deformable center portion that isresilient which frictonally engages an output member to act as a directdrive until a predetermined load force is exceeded when a clutchingaction takes place.

This invention relates to drive mechanisms and more particularly to adrive mechanism for an automobile window regulator having a clutchingarrangement.

Electric regulators for vehicles require that their operation cease whenthe window travel has reached predetermined limits. These limits can besensed by limit switches used to cut off drive motor operation or can besensed by stalling an electric drive motor at either limit of travel.The latter method has certain inherent economies so this disclosurerelates to that method. A

It is an object of the present invention to provide an improved drivemechanism for electric window lift motors that will allow slippagebetween the drive motor and the driven mechanism when limits of travelof the driven mechanism are reached.

It is another object of the present invention to carry out theaforementioned object and providing an audible sound indicating that aslippage is taking place.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

FIGURE 1 is an elevational view of a vehicle door with the subjectmechanism shown in its operative environment;

FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 1;

FIGURE 3 is a sectional view taken along line 3 3 of FIGURE 2.

Referring to FIGURE 1, the drive mechanism, generally designated by thenumeral 10, is illustrated as being mounted on the interior portion of avehicle door 12 driving windowsl 14 up and down between predeterminedlimits of travel.

Referring to FIGURE 3, an electric motor, not shown, has an output shaft16 carrying worm gear 18. Worm gear 18 is adapted to rotationally driverotatable means or gear 20. Gear 20 is composed of any wear-resistantresilient plastic and is integrally formed with a symmetrical center webarrangement 22 which includes a center deformable portion 24.

Referring to FIGURE 2, portion 24 is carried around four lobes 26 ofdrive means 28 with the lobes press t into portion 24. Drive means 28 isintegrally formed with gear 30 normally meshed with drive gear 32utilized to raise and lower the vehicle window 14. Drive means 28 iscarried on shaft 34 rotatably mounted in support members 36.

In operation, when it is desired to raise or lower window 14, the motor,not shown, is appropriately rotationally controlled to drive worm gear18 through shaft 16 in lCe the desired direction. Gear 20 rotates inresponse to worm gear 18 which rotation is transmitted through lobes 26to gear 30 and on to drive gear 32. Depending on the direction ofrotation of drive gear 32, the window is lowered or raised. When thepredetermined limit of movement of window 14 is reached, drive gear 32will stop, causing gear 24 and lobes 26 to also stop. The rotation ofworm gear 18 induced by the motor and the responding rotation of gear 20will continue. Portion 24 will slip relative to lobes 26 causing a noiseaudible to the vehicle operator. This noise signals that the mechanismhas reached the extreme of desired movement and alerts the vehicleoperator to release the switch bringing power to the electric motor. Thesame cycle of events takes place regardless of the direction of rotationof shaft 16, thereby providing a limiting means for the movement of thevehicle window.

Gear 20, along with web arrangement 22 and center portion 24, mustnecessarily be composed of a frictionresistant material, such as nylon,and the webs 22 must be of sucient rigidity as matched to the electricmotor to allow force transmission from the motor to gear 20 under givenload conditions by allowing slipping between portion 24 and lobes 26when a predetermined loading of the mechanism is experienced. Therefore,it becomes clear that the physical dimension of the gear 20 and webarrangement 22 are critical and must be matched to the motor used in agiven installation. Too much resistance to relative movement between thelobes 26 and portion 24 could result in motor damage or damage to thedrive mechanisms of the window lift arrangement. Therefore, the physicaldimensions of gear 20 and Webs 22 must be tailored to a particularinstallation.

While the embodiment of the present invention, as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is:

1. Drive mechanism comprising: a source of power; rotatable means drivenby said source of power, said rotatable means having a nonrigid centerdriven portion; and drive means resiliently carried and frictonally heldin an operative position by said rotatable means and responding torotation thereof to move a force operated device between extremes ofmovement.

2. Drive mechanism according to claim 1 wherein said nonrigid centerdriven portion of said rotatable means resiliently grips said drivemeans and maintains said rotatable means and said drive means rotatingin unison until a predetermined load force on`said drive means isexceeded.

3. Drive mechanism according to claim 1 wherein said drive meansincludes a lobed portion frictonally engaging said nonrigid centerdriven portion to provide a power transfer link for said source of powerto said drive means when a load on said drive means remains belowpredetermined limits, said lobed portion slipping relative to saidnonrigid center drive portion and creating an audible sound when load onsaid drive means exceeds predetermined limits.

4. A drive mechanism for operating a window regulator mechanism forraising and lowering a window of an automotive vehicle comprising: afirst gear which is adapted to be driven by an electric motor; a secondgear in meshed engagement with said rst gear and which is driven by thelatter; and a drive means adapted to be connected with a windowregulator mechanism, said second gear including a deformable centerportion provided with a generally central opening therein and said drivemeans having a portion received within said opening but which isfrictonally engaged by said deformable center portion, said frictionalengagement between said deformable center portion and said portion ofsaid drive means being such that said second gear is effective to rotatesaid 3 drive means when the load imposed on the latter bythe windowregulator mechanism is less than a predetermined value and said secondgear slipping and rotating relative to said portion of said drive meansand emitting an audible sound when the load imposed on the drive meansexceeds said predetermined value.

5. A drive mechanismy as dened in claim 4 wherei said opening in saidcenter portion of said second gear is noncircular and wherein saidportion of-said drive means is noncircular.

6. A drive mechanism according to claim 4 wherein said second gear is aunitary plastic member having resilient center support ribs formed in anet pattern around a deformable bearing portion which frictionallyengages said portion of said drive means. y

UNITED STATES PATENTS 1,447,390 3/1923 Kucharski 74-411 2,302,11011/1942 Dowet a1 64-30 2,537,672 'f1/1951121111@ f` 744411 3,067,627 l12/1962 Pickles 74 -425 3,144,91928/19641 Eqteetal. y 3,203,268 s/1965Manoni efa1;' k "74411 3,304,795, .2z/:1967

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington,D.C. 20231 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 406 583October Z2 1968 John P. Baier It is certified that error' appears in theabove identified patent and that said Letters Patent are herebycorrected as shown below:

Column l, line 23, after "Electric" insert window Signed and sealed this3rd day of March4 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

